Resumo

MRAD, Maroua; CHOUCHENE, Bilel  e  CHAABANE, Tahar Ben. Effects of zinc precursor, basicity and temperature on the aqueous synthesis of ZnO nanocrystals. S.Afr.j.chem. (Online) [online]. 2018, vol.71, pp.103-110. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2018/v71a13.

The effects of the zinc salt precursors, the reaction temperature and the alkaline ratio b (b = [OH-]/[Zn²⁺]) on the aqueous synthesis of ZnO nanocrystals were investigated. Depending on the type of the zinc precursor, Zn₅(OH)₈CL/H₂Oor Zn₅(OH)₈(NO₃)₂.2H₂O lamellar phases were obtained at room temperature (20 °C) when the alkaline ratio is lower (0.5 < b < 1, 6 < pH <£ 6.4). When the reaction temperature increased to 95 °C, zinc hydroxide chloride monohydrate was obtained in one case whereas zinc oxide was formed in the other, and no lamellar phase of Zn₅(OH)₈(NO₃)₂.2H₂O was obtained. Thermal decomposition of the two lamellar phases was carried out and mainly showed that Zn₅(OH)₈(NO₃)₂.2H₂O was completely decomposed to ZnO when the annealed temperature reached ~250 °C while Zn₅(OH)₈CL/H₂O was totally transformed to ZnO at about 400 °C, a higher comparative temperature that confirms the better thermal stability of the zinc hydroxide chloride monohydrate.

Palavras-chave : Oxides; ZnO; chemical synthesis; X-ray diffraction; crystal structure; luminescence.

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